Electron-beam deflection system



Oct. 17, 1961 s. GOLDBERG ETAL 3,005,128

ELECTRON-BEAM DEFLECTION SYSTEM Filed Oct. 18, 1957 ELECTRON BEAM FROM GUN ELECTRON TARGE T OR SCREEN (I 17/ ls INVENTORS KENNETH J. GE RMESHAUSEN BY SEYMOUR GOLDBERG WWW ATTORNEYS The present invention relates to electron-beam deflection apparatus and, more particularly, to cathode-ray deflection systems of the long traveling-wave type.

In copending application, Serial No. 591,339, filed June 14, 1956, for Cathode-Ray Apparatus and Method by Kenneth J. Germeshausen, Seymour Goldberg and Daniel F. McDonald, there is disclosed a traveling-wave deflection apparatus comprising a pair of helical windings formed about insulative spacers semi-circular in crosssection, with the diameter boundaries thereof disposed parallel to and spaced from one another to permit the electron beam or stream of the cathode-ray tube to travel between the windingsamflgdesigning the signal velocity along the axis of the windings to equal the electron-beam velocity between the windings, transit-time distortion is eliminated and high deflection sensitivity is attained.

Practical difliculties are encountered, however, in designing the deflection apparatus to attain the above results. In view of the coupling between adjacent turns of the windings, it is, indeed, difficult to obtain a satisfactory signal-transmission characteristic in the winding and there sometimes results a destruction of the highfrequency response characteristics of the deflection windings. In addition, the positions assumed by the pair of windings relative to the grounded conductive cathode-ray housing within which the deflection apparatus may be disposed, are interdependent and these is a decidedlimitation upon the possible spacing of the windings from one another and hence upon the actual size of the path therebetween available for the electron-beam flow. This, of course, limits the possible deflection range of the apparatus and the electron beam diameter.

I An object of the present invention, accordingly, is to provide a new and improved deflection apparatus of the above-described character that shall not be subject to these disadvantages but that shall, on the contrary, provide improved high-frequency response and greater latitude for relative positioning of thedeflection windings. In summary, this end is attained through the employment of a pair of flat-oval helical windings, each preferably disposed about a grounded planar conductive sheet. Further details of construction are later presented.

Other and further objects will be explained hereinafter and will be more particularly pointed out in the appended claims.

The invention will now be described in connection with the accompanying drawing of which FIG. 1 is a perspective View illustrating the invention preferred form, with parts broken away to show details of construction;

FIG. 2 is cross-sectional view, upon an enlarged scale,

taken upon the line 22 in FIG. 1, looking along the direction of the arrows; and

States W atent l ice or screen, so labelled. The electron beam or stream passing from the gun toward the target or screen, at a velocity determined by the adjustment of the gun .volt

ages, as is well known and as is explained, for example, in the said application, passes between a pair of spaced, coextensive, substantially parallelly oriented deflection windings 3, 3' of the traveling-wave helical type, but constructed in accordance with the present invention.

As before stated, it is desired to equate the deflection signal transit time along the deflection windings 3, 3' to the electron-beam transit time through the space between the windings. Since the electron-gun optics pre-determines the electron velocity, itis therefore necessary to construct the windings 3, 3' to have the required transmission-line characteristics'that can effect this equality, and to do so without destroying high-frequency response as a result of the turn-to-turn coupling of the windings. The problem involves, indeed, from the practical point of view, the minimizing of the electrical transit time per turn of the deflection winding while maintaining the required characteristics of the deflection apparatus. This problem is admirably solved in accordance with the invention, with the aid of ground planes inserted within each of the windings to reduce the current coupling between adjacent turns. Preferably, also, the winding itself is wound as close to the ground planes as feasible, in flat-oval fashion thereby to minimize the path length of each turn of the helix. More than this by employing wide ribbon or tape-like windings the spacing between the turns can be kept small. The close winding and ribbon spacing, however, are subject to the limitation-that they must produce the required efiective transmission-line impedance. The small spacing between adjacent turns,- moreover substantially eliminates any effect from the ground plane or the voltage field distribution between helices. This results in maximum sensitivity and minimum distortion. Note that required dimensions, width of tape, spacing to ground plane, pitch etc. can be calculated with good approximation by well known parallel plane transmission line formulas provided turn-to-turn coupling is small.

The ground planes are illustrated as substantially flat conductive plates 5, 5' about which the preferably ribbon or tape windings 3, 3' are closely wound in flat-oval fashion, more clearly evident in FIG. 2; .The plates 5, 5' extend beyond the windings at both ends and are there supported within the envelope 1 in fixed position by brackets 7 that may be brazed or otherwise secured to the inner wall of the envelope 1. The ground potential may thus be applied to the plates 5, 5 from-the prefer-ably FIG. 3 ,is a schematic longitudinal section of a modi- I grounded envelope wall 1.

The windings 3, 3' may, in turn, be supported by insulating rods or members 9, 9' running throughout their length and terminating in brackets, 11. The ends of the insulating rods 9, 9 pass through the brackets 11 and are secured to the ground-plate bi'akets? as'ai; The windings 3, 3' may thus be mechanically supported by the ground-plate brackets 7 and maintained closely wound about the ground-plane plates 5, 5 but out of electrical contact therewith.

Signal input and output connections may be conveniently and efiiciently provided by coaxial-line sections 15, 17, extending outside the envelope 1 with the outer conductors 15 in electrical contact therewith. The inner conductors 17 may pass within the envelope 1 to en gage the winding terminal brackets 11, as at 19, which may electrically connect with the ends of the winding.

Not only are the before mentioned difficulties attendant upon the use of prior-art traveling-wave deflection systemsthus-obviated by the present invention, but additional novel results are also obtained. Whereas, as before stated,

the positions assumed by the prior-art deflection windings.

were interdependent and the space available for the electron path therebetween was accordingly limited, the,

ground-plane plates 5, 5 of the present invention maintain ground symmetry for each winding 3, 3' so that the windings are substantially independent of one another one another throughout. The present invention, however,

permits of variationin the shape of the path defined between the helical windings'3, 3', so that, for example, the windings may diverge somewhat at an end, as shown to the right in FIG. 3, permittingtheattainment of improved deflection performance.

Ifthe improved sensibility described in the said copending application is to be obtained, the electron-beam focusitlg coils or other means F, FIG. 1, may'substantially centrally overlap the helical deflectionfield.

Further modifications will also occur to those skilled in the art, it being understood, for, example, that the mechanical' supporting structure illustrated and described is but one of many that could be employed to attain the novel resultsherein described, and all such are considered to fall within the spirit and scope of the invention as defined in the appended claims;

What is claimed is:

1. In a system having a-portion connected to ground, an electron-beam deflection apparatus comprising a pair of spaced co-extensive helical windings each wound about, but maintained out of electrical contact with, a conductive ground plate connected to said ground of the system, thereby to maintain ground symmetry for each Winding.

2. Electron-beam deflection apparatus comprising a pair of spaced co-extensive helical windingspositioned within a conductive envelope and each wound about, but maintained out of electrical contact with, a conductive ground plate connected to the envelope, thereby to maintain ground symmetry for each winding.

3. Electron-beam deflection apparatus comprising a pair of spaced co-extensive helical windings positioned Within a conductive envelope and each wound about, but maintained out of electrical contact with, a conductive ground plate connected to the envelope, thereby to maintain ground symmetry for each winding and signal-applying means comprising coaxial-line sections each connected to extend outside the envelope with the outer coaxial conductor connected to the envelope and the inner coaxial conductor passing through the envelope to connect with the helical windings.

4. Electron-beam deflection apparatus comprising a pair of spaced co-extensive helical windings within a conductive envelope, each winding being wound about, but maintained out of electrical contact with, a conductive ground plate, thereby to maintain ground symmetry for each winding, the ground plate having supporting means for holding the plate fixed within and in electrical contact with the envelope, the windings being insulatively and mechanically supported by the plate-supporting means.

5. Electron-beam deflection apparatus comprising a pair of spaced co-extensive helical windings within a conductive envelope, each winding being wound about, but maintained out of electrical contact with, a conductive ground plate, thereby to maintain ground symmetry for each winding, the ground plate having supporting means for holding the plate fixed within and in electrical contact with the envelope, the windings being insulatively and mechanically supported by the plate-supporting means, and signal-applying means comprising coaxial-line sections each connected to extend outside the envelope with the outer coaxial conductor connected to the envelope and the inner coaxial conductor passing through the envelope to connect with the helical windings.

6. Electron-beam deflection apparatus comprising a pair of spaced co-extensive fiat-oval helical windings of substantially flat conductive ribbon within a conductive envelope, each winding being wound closely about, but maintained out of electrical contact with, a conductive ground plate, thereby to maintain ground symmetrytor each winding, the ground plate having supporting means for holding the plate fixed within and in electrical contact with the envelope, the windings being insulatively and mechanically supported by the plate-supp0rting means, and signal-applying means comprising coaxial-line sections each connected to extend outside the envelope with the outer coaxial conductor connected to the envelope and the inner coaxial conductor passing throughthe envelope. to connect with the helical windings.

7. In a system having a portion connected to ground, an electron-beam deflection apparatus comprising a pair of; spaced co-extensive helical windings each wound about, but maintained out of electrical contact with, a conductive ground plate connected to said'ground of the system, thereby to maintain ground symmetry for each winding, the pair of ground plates and the corresponding windings diverging near an end to improve deflection performance.

8. In a system having a portion connectedto ground, an electron-beam deflection apparatus comprising a pair of" spaced co-extensive helical windings each Wound about, but maintained out of electrical contact with, a conductive ground plate that extends beyond both ends of the winding and that is connected to said ground of the system, thereby to maintain ground symmetry for each windmg.

9. Electron-beam deflection apparatus as claimed in claim 4 and in which the plate-supporting means comprises a bracket extending to the envelope wall and the winding supporting means comprises an insulative member extending along the winding and connected with the said bracket.

10. In a system having a portion connected to ground, an electron-beam deflection apparatus comprising a pair of spaced co-extensive helical windings each wound about, but maintained out of electrical contact with, a conductive ground plate connected to said ground of the system, thereby to maintain ground symmetry for each winding, the windings being disposed on opposite sides of the electron beam, with the space between the ground plate and the inner surface of the Winding free of im-' pedance discontinuities.

11. In a system having a portion connected to ground, an electron-beam deflection apparatus comprising a pairof spaced coextensive conductive ground plates disposed within an envelope, helical winding means wound about at least one of the ground plates but maintained. out of electrical contact therewith, means for applying electronbeam deflection current to said winding means, means forconnecting both said ground plates to said system ground, and means for projecting an electron beam between the said winding means and the other ground plate.

References (Iited in the file of this patent UNITED STATES PATENTS Haetf Dec. 15, 1936 (Other references on following page) UNITED STATES PATENTS Dohler Jan. 10, 1956 Walker Mar. 15,1956 Pierce July 30, 1957 Adler Oct. 8, 1957 Kompfner Oct. 21, 1958 Quate Sept. 6, 1960 

